I have tried this but the NT AUTHORITY\ANONYMOUS LOGON is still showing up in services > User activity on smoothwall, and builds up after a few days again with users report being banned as the smoothwall is seeing them as NT AUTHORITY\ANONYMOUS LOGON again.
This too has started since September for us.
Did you put anything else in LogonExclusions? Did you put NT AUTHORITY\ANONYMOUS LOGON in quotes as it has spaces?